Conventionally, there has been a rotary compressor as shown in FIGS. 6 and 7 (refer to Japanese Utility Model Laid-Open Publication No. SHO 61-114082). This prior art compressor is provided with a compression element A that is driven by a motor inside its hermetic casing. This compression element A includes a cylinder C having a cylinder chamber B, and a roller E that is closely mounted around an eccentric section D of a drive shaft extending from an electric motor. This roller E revolves inside the cylinder chamber B by the rotation of the drive shaft. Furthermore, the compression element A has a blade H. This blade H is arranged between a suction port F and a discharge port G formed at the cylinder C so that it is allowed to advance and retreat there. Further, the blade H is operated by a part of a high-pressure gas discharged from the discharge port G used as a back pressure. A tip end portion of the blade H is always put in contact with a part of an outer peripheral surface of the roller E by the back pressure. With this arrangement, the blade H partitions the cylinder chamber B into a compression chamber X and a suction chamber Y. Further, a valve seat is formed around the exit of the discharge port G. To this valve seat is fixed an end portion of a valve I. This valve I can open and close the discharge port G.
In the compressor having the above structure, the roller E revolves inside the cylinder chamber B when the drive shaft D rotates. This revolving roller E compresses a gas in the compression chamber X partitioned by the blade H in the cylinder chamber B. Subsequently, when this compression process is completed to proceed to a discharge process, the roller E opens the valve I by the compressed high-pressure gas to discharge the high-pressure gas from the discharge port G into a casing.
When the discharge process is completed to proceed to a suction process, the valve I closes the discharge port G. Then, the roller E revolves to inhale a low-pressure gas from the suction port F into the suction chamber Y partitioned by the blade H in the cylinder chamber B. Thus, the roller E repeats the compression process and the discharge process while revolving in the cylinder chamber B.
However, in the above compressor, the blade H is supported by the cylinder C to be allowed to advance and retreat, where the blade H and the roller E are relatively moved with the tip end of the blade H put in contact with the outer peripheral surface of the roller E by the back pressure. Therefore, it is required to exert the back pressure on the blade H to press the tip end of the blade H against the outer peripheral surface of the roller so as to put them in contact with each other. Furthermore, since the portion of the blade H put in contact with the outer peripheral surface of the roller is lubricated little, they are put in a boundary lubrication state. In this boundary lubrication state, a metallic contact tends to occur, and this possibly causes seizure problematically.
Also, when an HCFC (hydrochlorofluorocarbon) group fleon refrigerant (e.g., R22) is used as a working fluid for use in a compressor, a chloride film is formed by the chlorine contained in the fleon refrigerant even when a deficient lubrication occurs, and the chloride film has suppressed the seizure to some degree.
However, when using an HFC (hydrofluorocarbon) group substitute fleon refrigerant (e.g., R134a), the lubricating oil (mainly a synthetic oil) used in adaptation with the substitute fleon refrigerant has a lubricating capability lower than that of the lubricating oil (mineral oil) that has been used with the conventional fleon refrigerant. Furthermore, the substitute fleon refrigerant is not containing chlorine, and therefore, no chloride film is formed. Therefore, in the portion of the boundary lubrication, a temperature rise partially occurs to cause such a problem that the oil deteriorates to incur a hydrolysis or generate a sludge.
Furthermore, in the refrigerating apparatus in which the prior art rotary compressor is incorporated into its refrigerating circuit, when a capillary tube is used as a pressure reduction mechanism of the refrigerating apparatus, a great amount of sludge generated due to the oil deterioration adheres to the inside of the tube. The adhesion of sludge incurs the reduction in flow rate of the refrigerant, and this problematically impairs the reliability of the refrigerating apparatus.
Accordingly, in view of the above-mentioned problems, it is an object of the present invention to provide a rotary compressor capable of preventing the oil in the compressor from deteriorating while using a substitute fleon refrigerant. Another object of the present invention is to improve the reliability of the refrigerating apparatus by providing a refrigerating apparatus having a rotary compressor free from the occurrence of oil deterioration.